Scenario A: The supposedly inept president of the United States carefully planned and orchestrated the worst terrorist attack on American soil in our history. Though "only" 3,000 people died, the plan was to kill many more by simultaneously attacking the World Trade Center, the Pentagon and either the U.S. Capitol or the White House itself on Sept. 11, 2001.

Hundreds of people, including personnel from myriad agencies, participated. According to some versions of Scenario A, explosives were placed at the World Trade Center to ensure success. In other versions, all of "the Jews" working there were tipped off by some phone bank run by the Mossad. In every version, however, the U.S. government was in on it, and everyone involved kept the biggest secret in American history.

Then, there's Scenario B: An ambitious and extremely clever politician, who has at best been selectively forthcoming about large chunks of his youth, lied about his place of birth so he could be eligible for the presidency.

To further this scheme, he has arranged for the full and/or original version of his birth certificate to remain under lock and key. At most, a handful of supporters and lawyers are in on the whole thing.

Now, which one is more believable? For the record, I don't believe either. But it seems to me the "birther" hypothesis is vastly more plausible than the "truther" hypothesis. Politicians lie to advance their careers. You can look it up. Whole governments rarely orchestrate incredibly complex acts of physics, logistics and mass murder all the while pinning guilt on others (who boast that they acted alone).

The question of which scenario is more plausible is neither academic nor trivial. This summer, a host of columnists, commentators and activists, seemingly taking their cues from a White House and DNC public-relations offensive, declared that the rise of the "birthers" was a fatal indictment of modern conservatism and the Republican Party. The refusal of the birthers to give up their cockamamie theory was proof that the GOP had succumbed to the "paranoid style." Indeed, according to some liberal commentators the birthers were the potential wellspring for a nascent Nazi movement in America. Never mind that the vast majority of leading Republicans and conservatives -- from Newt Gingrich to Ann Coulter -- rejected the birthers categorically.

Fast-forward to the last week or so. Van Jones, an avowed "communist" and passionate supporter of convicted cop killer Mumia Abu-Jamal, was a truther par excellence. Contrary to many reports, he didn't merely sign 911truth.org's petition in 2004, he helped organize one of the first truther groups as early as 2002.

When these and other revelations came to light, Jones resigned from his White House job as "green jobs czar."

The reaction from much of the liberal establishment has been fascinating, hypocritical and deeply creepy. For starters, the same White House that fueled the anti-birther boom has refused to offer a single critical word about Jones' past positions (some of which he recanted as his job security grew more threatened; we'll see how long that lasts).

In July, the popular left-wing Web site FiredogLake couldn't let go of the birther bit. One post -- titled "The Republican Party is the Birther Party, and it's dragging them down" -- made much of the fact that 28 percent of Republicans, according to one poll, do not believe that Obama is a natural-born citizen. This week, the site's founder, Jane Hamsher, was disgusted that Jones was "thrown under the bus," even though he subscribed to trutherism, a view that "35 (percent) of Democrats believed as of 2007."

Got that? Belief in an implausible conspiracy is a cancer on the GOP. Even greater belief in an even more implausible conspiracy is proof that it's mainstream.

Apologies for Jones and trutherism appeared instantly on the sites of the left-wing flagship magazines The Nation, The New Republic and elsewhere. The New York Times and Newsweek deliberately distorted what the truthers believe in order to make Jones look more reasonable and his critics more unreasonable. The Financial Times actually reported that Jones resigned for criticizing how the GOP majority had run Congress.

But mostly, the mainstream press changed the subject to how the right is paranoid and vaguely unpatriotic for opposing Obama's speech to schools Tuesday, despite the fact that most conservatives and Republicans didn't protest the speech once the Department of Education's controversially politicized lesson plans were withdrawn.

One last question is worth asking. Forget which is more plausible.

Which scenario is more unpatriotic, more malicious, more corrosive to civic life? In short: which is more evil? Again, I think the answer is obvious. Alas, it seems I'm in a minority.